Products involving copper composition materials and assemblages

ABSTRACT

Copper, pure or alloyed and alone or in the presence of associated components, is enclosed within an iron or steel &#39;&#39;&#39;&#39;can, &#39;&#39;&#39;&#39; i.e., casing. When this system is heated, (1) there is a tendency for any oxygen present to transfer from the copper to the iron, and (2) there is a tendency for the iron and the copper to avoid interdiffusion. The result is an unexpected though simple technique for controlling oxygen in a variety of novel copper processes and the consequent feasibility of a variety of novel copper products. Thus copper and iron constitute a synergistic pair in connection with the contemplated can processes and products.

United States Patent [191 Finaly et al.

[4 1 Apr. 30, 1974 [54] PRODUCTS INVOLVING COPPER 1,615,994 2 1927 Morrison 148/4 x COMPOSITION MATERIALS AND 3,297,484 l/l967 Niedrach ASSEMBLAGES 3,574,569 4/197] Vordahl 29/ 196.6

[76] Inventors: Walter L. Finaly; Donald A. Hay; primary Examiner A. 3 Curtis Wendell F do Copper Assistant Examiner-O. F. Crutchfield f Attorney, Agent, or FirmMorse, Altman, Oates & [22] Filed: Oct. 13, 1972 Belle [2]] App]. No.: 297,424

. [57] ABSTRACT Related US. Application Data C ti f f S N 854 961 s t 3 1969 Copper, pure or alloyed and alone or 1n the presence g' 'gi g il g of associated components, is enclosed within an iron Jan. 24 19157 Pat No 3 474 516 or steel can, i.e., casing. When this system is heated, (1) there is a tendency for any oxygen present to 52 US. (:1. 29/1875 transfer from the iron and (2) there is a 51 Int. Cl B21b 1/00 B32b 15/00 tendency the iron and amid imerdif' [58] Field of Search 29/187 5 fusicm- The result is an unexpected though Simple technique for controlling oxygen in a variety of novel [56] References Cited copper processes and the consequent feasibility of a variety of novel copper products. Thus copper and UNITED STATES PATENTS iron constitute a synergistic pair in connection with .Ohl'lSOI: et a] 29/4709 the contemplated can processes d products rasser 2,707,323 5/1955 Watson 29/4709 3 Claims, 6 Drawing Figures PATENTEDAPR 30 1914 3:807; 988

' sum 2 or 2 FIG. 4

ATTORNEYS PRODUCTS INVOLVING COPPER COMPOSITION MATERIALS AND ASSEMBLAGES RELATED APPLICATIONS This is a continuation of application Ser. No. 854,961, filed Sept. 3, 1969, and now abandoned, which is a division of Pat. application Ser. No. 61 1,294, filed Jan. 24, 1967, now US. Pat. No. 3,474,516, in the name of the applicant hereof for Processing Of Copper Composition Materials And Assemblages Within Iron Composition Casing, And Products Thereof.

BACKGROUND OF THE INVENTION The present invention relates to the processing of copper metals, i.e., copper and copper alloys, and, more particularly, to the conditioning and working of copper metals following converting.

Generally, extraction of copper from an ore such as chalcopyrite (which contains the copper primarily as the sulfide) involves: milling the ore to fine particle size; froth flotation by which copper rich particles in an aqueous suspension adhere to gas bubbles that rise to the surface of the suspension where the copper rich particles are collected and concentrated; roasting the concentrate to eliminate water and to oxidize some of the sulfur; smelting to eliminate unwanted residues as slag and to separate the copper therefrom in the form of cuprous sulfide; and converting the cuprous sulfide to metallic copper by oxidizing the sulfur to sulfur dioxide, which becomes separated as a gas. Since sulfur, even in very small concentrations, in copper tends to increase brittleness and reduce conductivity, it must be removed completely with the aid of a slight excess of oxygen. The result is copper oxide formation. Oxygen, though not to the same degree as sulfur, tends to have a similar effect but has been relatively expensive to remove and control. The present invention is concerned with the removal or control of such oxygen, and with certain products made feasible thereby.

SUMMARY OF THE DISCLOSURE The primary object of the present invention is to provide products involving the removal or control of oxygen from a copper metal composition of the foregoing type, in the following manner. The copper metal composition, including any desired non-copper components, is enclosed within a close fitting can, i.e., casing. The can characteristically contains iron and, depending upon its composition, is either reactive or unreactive with respect to oxygen. When the can is reactive, it is capable of gettering oxygen from the copper metal composition, on heating, in order to render it or optionally its surface oxygen free. When the can is unreactive, it is capable to isolating its contents from ambient oxygen while providing a controlled chemical environment for its contents. In both cases, the copper metal composition may be mechanically worked while in the can in such a way that, despite deformation of the can along with its contents, removal of the can from its contents at the end of the process is not difficult. In accordance with the present invention, therefor, copper and iron constitute a synergistic pair.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

For a fuller understanding of the nature and objects of the present invention, reference is to be had to the accompanying drawing wherein:

FIG. 1 is a schematic flow diagram illustrating copper deoxidation in accordance with the present invention;

FIG. 2 is a schematic flow diagram illustrating clad coper metal production in accordance with the present invention;

FIG. 3 is a schematic flow diagram illustrating copper powder compacting and sintering in accordance with the present invention;

FIG. 4 is a schematic flow diagram illustrating copper winning and consolidating in accordance with the present invention;

FIG. 5 is a schematic fiow diagram illustrating dispersoid strengthening in accordance with the present invention; and

FIG. 6 is a schematic flow diagram illustrating slab consolidating and working in accordance with the present invention.

SPECIFIC DISCLOSURE The products described specifically hereinbelow are produced by a combination of two or more of the following steps, insofar as such steps are not inconsistent: (1) enclosing a metallic mass of a copper composition in a metallic can of an iron composition; and/or (2) predeterrninedly heating the entire assemblage to a temperature at which oxygen diffuses to the surface of the copper, oxygen is released from the surface of the copper, oxygen migrates to the surface of the iron and oxygen reacts with the iron to form a stable solid; and- /or (3) heating the entire assemblage to a temperature at which some chemical or physical change other than copper deoxidation occurs; and/or (4) mechanically working the entire assemblage with the can remaining sealed; and/or (5) removing the can from its contents by chemically dissolving or mechanically stripping. Various examples of combinations of these steps are given in the six examples below, which are illustrated in the six figures of the drawing.

Generally, the copper metals useful in accordance with the present invention include commercial bulk and particulate copper and various copper alloys. Contemplated commercial bulk or particle copper, for example typically includes the following.

1. Electrolytic Tough Pitch (ETP) copper which contains by total weight in a remainder of copper: combined oxygen in the form of Cu O and dissolved oxygen 0.04 percent; and nickel, iron, bismuth, arsenic trace;

2. Lake Copper, which contains by total weight in a remainder of copper, from 0.05 to 0.089 percent silver, in addition to minor proportions of oxygen, nickel, iron, bismuth and arsenic, as specified above in connection with ETP copper;

3. Oxygen Free (OF) Copper, containing by total weight in addition to a remainder of copper: iron 0.0005 percent; sulfur 0.0025 percent; silver 0.001 percent; nickel 0.0006 percent; tin 0.0002 percent; arsenic 0.0003 percent; selenium 0.0002 percent; tellurium 0.0001 percent; lead 0.0006 percent; antimony 0.0002 percent; manganese 0.0005 percent; bismuth 0.0001 percent; and oxygen 0.0002 percent.

When deoxidation is contemplated, the copper alloys are those containing copper as their characteristic ingredient, preferably in excess of 50 percent by total weight, and one or more other metals that are less active than iron, namely cadmium, cobalt, nickel, tin, lead, arsenic, rhenium and bismuth. These metals have a lower negative free energy of oxide formation than iron. The physical form of the copper metal is either one or more solid cast cakes or fine particles When deoxidation is to be avoided, other alloying metals may be employed.

Generally, the iron composition of the can is a low cost metal such as follows. A typical wrought iron composition for the foregoing purpose, by total weight contains: carbon 0.02 percent; manganese 0.03 percent; phosphorous 0.12 percent; sulfur 0.02 percent; silicon 0.15 percent; iron remainder. A typical acid bessemer, mild steel for the foregoing purpose, by total weight, contains: carbon 0.07 percent; manganese 0.35 percent; phosphorous 0.10 percent; sulfur 0.05 percent; silicon 0.02 percent; and iron remainder. A typical open hearth, mild steel for the foregoing purposes by total weight, contains: carbon 0.10 percent; manganese 0.40 percent; phosphorous 0.03 percent; sulfur 0.03 percent; silicon 0.02 percent; and iron remainder. A typical stainless steel for the foregoing purpose, by total weight contains: nickel 18 percent; chromium 8 percent; carbon 0.03 percent; and iron remainder.

Preferably the thickness of the iron can, depending upon the size of the assemblage and upon the contents to be deoxidized, ranges from to 1 inch or more, a typical thickness being one-fourth inch.

Generally, oxygen removal from the copper composition within the can is effected in a vacuum which is produced by exhausting the can through an opening to a pressure as low as conveniently possible, e.g., below 20 mm. Hg., preferably in the range of 0.1 to 1.0 micron mm. Hg, in order to reduce the demands on the gettering agent which is constituted either by the iron can itself or by a large surface iron configuration in the can.

After evacuation, the opening in the can is sealed and the can is heated, together with its contents, to a temperature within the approximate range l,400 to 1,800F. for the period necessary to effect deoxidation to the degree and depth desired. The gettering process may be enhanced either by a gaseous transfer agent or a solid large surface deoxidizing agent, the former of which may be introduced into the can following evacuation of air and the latter of which may be introduced into available space in the corners or at the edges of the can. A suitable gaseous transfer agent is hydrogen, which may be utilized only when not in too large a concentration, preferable when at a pressure of less than 20 mm. Hg. The arrangement is such that the hydrogen reacts with the oxygen to form water vapor not only with surface oxides but also with copper oxides in the interior of the Cu. Water vapor formed on the surface of the Cu migrates over the Fe can or getter in the can, reacts with it to form stable iron oxide and hydrogen. Some of the latter diffuses out through the Fe can and is lost; most, however, migrates back to deoxidize more Cu. Water vapor formed in the interior of the Cu causes fissuring of the copper mass. However, if the copper mass is retained within the can during hot rolling, the fissures are welded together. Suitable solid gettering agents, such as finely divided iron powder or steel wool, also, may be employed. The gettering procedure can be continued either to a point at which the surface only of the copper is deoxidized or to a point at which the entire copper mass is deoxidized.

Generally the copper composition contents of the iron composition can may be worked advantageously without separation following deoxidation. The reason for this possibility is that iron is more or less inert to copper, forming no intermetallic compounds therewith and having relatively low solid solubility therein. Thus, if the copper has an appreciable amount of oxygen, the iron will getter it to form brittle iron oxide at the interface, by which the iron later may be easily peeled from the copper and by which solid state diffusion of iron into the copper is blocked. If the copper has no appreciable concentration of oxygen, the largely inert iron simply welds to the copper surface and can be removed by pickling, for example in sulfuric acid. Alternatively, in the latter case, a release barrier may be interposed between the iron and the copper, for example, aluminum oxide powder, may be interposed in order to establish a release interface.

If, as in the case of Lake Copper, iron oxide particles are present in the copper mass, hydrogen should not be used. Rather iron should be used since it has been discovered that deoxidation by solid iron in a vacuum outside the copper mass will not affect iron oxide within the mass. This is fortunate since if the iron oxide particles were deoxidized, the iron, by virtue of its fine size and intimacy with the copper, would diffuse into the copper mass and thereby reduce the electrical conductivity.

The following non-limiting examples further illustrate the present invention.

EXAMPLE I FIG. l

A typical product embodying the present invention, is produced as follows: An as-cast, unconditioned Lake Copper cake is encased in a steel can 12, an opening 14 being left in the jacket to permit evacuation. As shown in exaggerated fashion, the copper cake has copper oxide imperfections at 16, 18 and 20 and contains iron oxide grains at 211. The can is evacuated through opening R4 to a pressure below about 1 mm. Hg. The opening then is closed by hammering or bending the pipe shut and welding it completely sealed before disconnecting the vacuum pump. Thereafter the can, is heated to a temperature of approximately 1,800F. This temperature and pressure are maintained for a sufficient period to enable copper oxide to decompose into copper and oxygen to migrate through the void separating the copper cake and the steel can to form iron oxide at 22 and 24. lron oxide particles 21 within the copper cake are unaffected. Optionally this temperature and pressure are maintained for a sufficient period to enable the decomposition of copper oxide parti cle 20, the diffusion of the resulting oxygen through the copper cake and the migration of oxygen to the steel can where iron oxide forms as at 25. Thereafter, the copper cake, while within jacket 12 is hot rolled to form a steel-copper-steel sandwich at a temperature of 1,600F. Finally the steel jacket is removed by pickling in sulfuric acid. Thereafter further hot and cold rolling are effected to produce copper sheet as at 27.

EXAMPLE ll FIG. 2

A slab of copper 30 is interposed between two slabs of cupronickel 32, 34, the thickness of the three slabs bearing the relationship cupronickel 15 percent; copper 7.0 percent; cupronickel 15 percent. The total slab, approximately 8 inches thick, 2 feet wide and 10 feet long, is enclosed within a A-inch thick mild steel can 36. The entire assemblage is heated to a temperature ranging from l,000 to 1,400F. while hydrogen is passed through the can to reduce all the copper and nickel oxides. The ports 38, 40, which permit the passage of hydrogen through the can, then are closed. The entire assemblage next is heated to hot rolling temperatures of from l,400 to l,800F. and the entire assemblage is rolled to provide one monolithic metallic blank 39. Next the entire assemblage is cold rolled to about 50 percent more than final thickness. Then the steel sheath 41, 42 is removed by pickling in sulfuric acid. Finally the cupronickel-copper-cupronickel sandwich is cold rolled to ultimate thickness.

In an optional modification of the present example, the hydrogen deoxidation step is replaced by deoxidation by reaction with the iron of the can.

EXAMPLE Ill FIG. 3

Copper powder 44, approximately 325 mesh in particle size, is placed in a mild steel can 46 that is 10 feet long by 2 feet wide by 6 inches deep and A-inch thick. The apparent density of the copper powder is about 0.15 pounds per cubic inch. Next the can is evacuated at room temperature through a port (not shown) and the port is welded shut. The assemblage is heated to a temperature of l,600 to l,800F. The base 48 of the can supports a pair of thick mild steel blocks 50, 52 for a reason now to become apparent. As a result of the heating, the copper powder sinters together into a compact mass approximately one-half its original volume. Since the inside of the can has been evacuated and since /i-inch mild steel at 1,600F. is not very strong, the top of the can collapses as at 54. Buckling of the edges of the can is prevented by blocks 50, 52. The combination of the box construction of the can and the sintered coherency of the copper powder permits hot rolling the can to a thickness of about one-half inch. The steel sheath now is stripped from the resulting copper sheet and the copper sheet finally is cold rolled to its ultimate thickness.

EXAMPLE IV FIG. 4

The dimensions of the can used in the following winning and consolidation process are the same as were the dimensions in Example Ill. Cu O and Cu S powders 60, 62 are mixed and placed in a mild steel can in proportions that are stoichiometric with respect to the oxygen and sulfur. Heating at 1,700F. while evacuating is effected in accordance with the formula:

Following evacuation of all S evolved, the port through which the S0 is evacuated is welded shut. Sintering, rolling and stripping then are effected as in Example lll.

EXAMPLE V FIG. 5

A dispersoid strengthened copper composition is produced in accordance with the present invention as follows. A can of the dimensions specified in Example I" is filled with a mixture of copper and aluminum particles. The copper particles contain just enough oxygen as oxides and in solid solution to react with all the aluminum metal in the aluminum powder. Hence the inner surface of the can is rendered inert, as by oxidizing or coating with M 0 powder so it does not gather the oxygen. Next the can is evacuated and sealed. When the assemblage is heated to l,800F., several reactions occur. Cu O decomposes to Cu and 0 Al expands more than A1 0 but any particles A1 0 coating that thereby cracks is promptly repaired by the 0 from the Cu O, whereby molten Al is prevented from running onto the Cu. The Cu powder sinters together as in Example III. Then the entire assemblage is hot rolled. During the rolling procedure, a thin film of molten Al, from the core of every Al particle which consists of said metallic Al core in an A1 0 coating, is smeared onto the surfaces of the Cu particles. This Al reacts with any Cu O on the surface of the Cu particles, and also, by interdiffusing with the Cu, which contains some dissolved oxygen as well as some discrete particles of Cu O, contacts oxygen inside the Cu and reacts to form sub-micron sized A1 0 dispersed particles 68. Removal of the mild steel sheath and cold working then results in dispersoid strengthened copper.

EXAMPLE VI FIG. 6

The process for producing the product of Example I is repeated except that four bulk copper slabs, each of the dimensions of the total slab indicated in Example II, are enclosed in superposition, snugly within a can of four times the volume as the can of Example II and with a can wall thickness correspondingly greater, e.g., 1 inch thick. Deoxidation and working under the conditions specified in Example 1 result in the consolidation of the slabs into a copper sheet of plate 78, whose overall mass is four times that of a single slab.

CONCLUSIONS The foregoing disclosure has shown and described various processes involved in enclosing a copper containing assemblage in an iron containing can. The can provides a versatile self-contained environment that is useful in effecting deoxidation to produce oxygen free copper, consolidated particles and slabs that are worked to integrated final products, to win refined copper, on copper whose alloys, from compounds such as copper sulfides and oxides, and copper that is strengthened by dispersoid particles. The iron of the can either participates in a reaction therewithin or is shielded from the reaction by its own composition or by an inner inert coat.

Since certain changes may be made in the foregoing disclosure without departing from the invention herein involved, it is intended that all matter described in the foregoing specification or shown in the accompanying drawings be interpreted in an illustrative and not in a limiting sense.

What is claimed is:

l. A metallurgical product comprising a hermetically sealed can, and a snugly confined charge within said can, said charge containing copper as its essential ingredient, said can containing iron as its essential ingredient, said can having a wall thickness ranging from A; to 1 inch, a gas within said can, the pressure of said gas within said can being less than 20 mm Hg, said gas containing hydrogen in sufficiently high concentration and oxygen in sufficiently low concentration to remove oxygen from said copper by migration from said copper and reaction with said iron.

2. The metallurgical product of claim 1 wherein said charge is a solid slab.

3. The metallurgical product of claim 1 wherein said charge is a powder. 

2. The metallurgical product of claim 1 wherein said charge is a solid slab.
 3. The metallurgical product of claim 1 wherein said charge is a powder. 